Dry etching processes, such as plasma etching processes, are employed in the fabrication of integrated circuits, primarily for producing fine structures. An etching mask, generally in the form of a photoresist pattern, will be transferred as dimensionally stable as possible into an underlying layer to be patterned. A layer following the layer to be etched or to be structured normally is not to be etched. For satisfying these requirements, an etching process to be used, for example, a chemical-physical dry etching process, has to have a high degree of anisotropy and great selectivity with respect to the underlying layer and the etching mask. The layers or material surfaces to be etched may, for example, comprise silicon (monocrystalline, polycrystalline or amorphous), SiO2, Si3N4, metals (e.g., aluminum), metal silicide or organic polymer layers.
In chemical-physical dry etching methods, material layers are structured such that superfluous material areas are etched away by means of etching masks. In these processes, by etching, a passivation layer (polymer layer), which has a protective function during the etching process and guarantees for anisotropy of the etching procedure, but which is undesired after the completed etching process and has to be removed completely, possibly using expensive solvents with wet-chemical methods, for example, may form on parts of the structured material layers. At the same time, this procedure also creates an increased environmental burden.